1. Field of the Invention
The present invention relates to a battery, and more particularly, to a battery having a coolant passage for better cooling efficiency.
2. Description of Related Art
In recent years, growing environmental consciousness has led to a movement to shift the power sources of vehicles from engines using fossil fuels to motors using electrical energy.
The technologies of batteries and cells, which are the power sources of the motors, have also been developed and advanced rapidly.
A battery to be mounted on a hybrid vehicle is required to be compact and lightweight as well as capable of charging and discharging high power frequently. The battery is also required to have excellent shock-proofness and heat radiation characteristics.
A battery disclosed in the Japanese Patent Application Laid-open Publication No. 2000-195480 is one in which a plurality of flat cells are arranged in an outer frame member. Given spaces are provided between each cell by interposing spacers therebetween, so that each cell has good heat radiation characteristics, thus improving the cycle characteristics and the rate characteristics (discharge characteristics) of the battery.
The use of a flat unit cell in the above-mentioned battery makes energy density higher as compared with a battery composed of non-flat cells (for example, cells in a cylindrical or a rectangular shape), contributing to downsizing the battery. This means that the battery of flat unit cells will be suited for the battery mounted on vehicles because of its compactness and high energy density.